December 12, 2025

@michaelokun

Did the late Mark Hallett crack the code underpinning the physiology of free will? Physiology refers to the study of how living systems function, including how the brain generates movement and the feeling of intending to move. Free will is the brain’s constructed awareness that we are choosing our actions even though the brain initiates them before we consciously know it. Mark Hallett was instrumental in describing how the brain prepares movement long before we become aware of choosing to act. Key Points: - Movement begins subconsciously as brain regions like the SMA and premotor cortex ramp up activity long before awareness of intention. - The perception of choosing to move appears to be constructed in parallel w/ movement generation, rather than driving the movement itself. - Parietal and insular networks help create the sense of agency by comparing internal signals w/ actual movement outcomes. My take: Free will is such an important topic and Mark spent a chunk of his career helping us to define it. Here are 5 points that resonated w/ me from his seminal article on the topic: 1- Movement starts before awareness, revealing that the brain prepares actions behind the scenes. 2- Intention is a brain perception, however it feels powerful and real in daily life. 3- Different brain networks shape free will including frontal areas for planning and parietal regions for sensing agency. 4- Neurological conditions reveal mismatches where movements occur w/out the usual sense of intention. 5- Understanding these systems can guide care as health care providers help folks manage movement disorders where will, intention and action become uncoupled. RIP to the great Mark Hallett and thank you for leaving a strong legacy. https://onlinelibrary.wiley.com/doi/full/10.1002/ana.24657 #michaelokun #fixelinstitute #parkinson